1. Field of the Invention
The invention relates to a method for reconditioning returnable barrels of sheet metal, which are embodied as bung barrels for their initial use and comprise a top cover, fixedly connected to the barrel wall and having a fill and discharge bung. For their further use, the bung barrels can be reconditioned to lid barrels by cutting out the top cover and providing bung lids or bung-free lids in its place, which lids are connected by a clamping ring closure to the outwardly rolled opening rim of the barrel wall. The upper portion of the barrel wall of the bung barrels forming the barrel neck is recessed or tapers relative to the opening rim of the barrel wall and, when manufacturing the bung barrel, the top cover with its rolled outer rim is placed onto the opening rim of the barrel wall and is connected thereto by lock-seaming and welding.
2. Description of the Related Art
The stringent environmental protection regulations require a transition from single use packagings to returnable packagings, such as, for example, barrels of steel or plastic, the conversion to packagings with greater volume with the goal of reducing the residual amounts, and the development of new returnable containers which, with respect to protecting the environment from harmful substances, can be reconditioned and can be optimally emptied with respect to residual amounts as well as easily cleaned for the reconditioning process as well as for a proper disposal by a pollutant-free destruction, for example, by combustion, or for recycling of the manufacturing material.
The development of reconditionable returnable barrels of sheet steel resulted in the reconditioning method described in DE 196 41 172 A1 with which bung barrels, after the first transport or the first storage of liquid material, classified as a great hazard posing a threat to the environment, and after discharge of the dangerous liquid material, can be reconditioned to lid barrels for further use as transport and storage barrels for granular and powder-like as well as paste-like materials, classified as a low hazard, with relatively minimal expenditure. Such lid barrels facilitate the filling as well as the discharge of the contents and provide the possibility of a direct action on the container contents, for example, by means of a simple stirring device, in contrast to bung barrels with a top cover which is connected by lock-seaming to the barrel wall, in which case the contents of the barrel can only be stirred by means of a complex stirring device, for example, configured as a folding propeller, that is to be introduced through the fill and discharge bung of the barrel.
The lid barrels which are reconditioned according to the method of DE 196 41 172 A1 from bung barrels cannot be used for transport and storage of liquids because the closure lid does not comply with the tightness requirements under external force impact, especially in drop tests. Moreover, when cutting off the top cover from the body of the bung barrel by a separating cut performed perpendicularly to the longitudinal center axis at the level or in the area of the center point of the rolled opening rim of the barrel wall, there is the risk that the rolled barrel rim will be damaged.
It is an object of the present invention to provide a cost-efficient method for-reconditioning bung barrels of sheet metal to lid barrels which can be used for the transport and storage of liquids as well as powder-like and granular as well as paste-like materials.
In accordance with the present invention, this is achieved in that, during reconditioning of the bung barrels to lid barrels, a circular cut is performed concentrically to the longitudinal center axis of the barrel through the transition area between the plate of the top cover and the inner rim of the top cover for separating the plate of the top cover from the barrel wall and in that the lower portion of the inner rim of the top cover is formed to an annular circumferential inner groove of the barrel neck.
By performing, in accordance with the reconditioning method of the present invention, a circular cut concentrically to the longitudinal center axis of the barrel through the transition area between the plate of the top cover and the inner rim of the top cover, the top cover of a bung barrel comprised of sheet metal can be separated from the barrel wall without damaging the outwardly rolled upper rim of the barrel wall. By forming the lower portion of the inner rim of the top cover, which is exposed after separating the plate from the top cover, into an annular circumferential inner groove of the barrel neck, the barrel neck is reinforced such that the barrel lid complies with the tightness or sealing requirements for drop tests so that the reconditioned lid barrel can be used for liquids. Furthermore, the risk of injury caused by the sharp edges of the inner rim of the top cover that remain after cutting is excluded.